(1)化简:8(a-b)2+4(a-b)+5(b-a)-6(b-a)2
(2)化简:3x3-[x3+(6x2-7x)]-2(x3-3x2-4x)
(1)
(2)15x
连词成句,注意单词的大小写及标点符号。
1. your, what, head, to, happened (?)
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2. a, we, watermelon, bought, so (.)
3. watermelon, Sam, the, carried, bikc ,the, on (.)
4. his, then, fell, Sam, bike, off (. )
一单能X射线通过3个半值层的厚度后强度为原来的()
A.1/2
B.1/3
C.1/4
D.1/8
E.1/16